This invention relates generally to ground fault detectors and more particularly, it relates to a ground fault and fire detector system for interruption of power lines upon sensing a fault current which exceeds a pre-determined level or upon a current flow from a fire extinguisher system. The ground fault and fire detector system of this invention has particular application in industrial or commercial plants, manufacturing facilities, restaurants, kitchens, home workshops, basements, assembly lines, public buildings and virtually any other facility where a hazardous condition could arise due to a ground fault.
It is commonly known that a ground fault is defined by a failure in an electrical circuit permitting leakage current or fault current to flow therein from a hot wire to ground. Such ground faults occur for many reasons such as from worn insulation, moisture, deterioration in equipment from age or abuse and from line-to-line short-circuits in power lines.
Generally, it has been encountered that such leakage current can likewise exit between a ground on equipment and/or other electrical devices in industrial facilities, plants, and the like and the earth ground which is also a potential source of danger or hazard to operating personnel in such areas. Particularly, when a fault current occurs there is a possibility that the personnel in these areas may receive a sudden electrical shock upon touching the equipment or even become electrocuted to death upon contacting the equipment.
Another problem exists when a fire condition arises in a building or plant creating a dangerous potential whereby it is necessary to disconnect the power lines to minimize serious injury. A fire extinguisher system is typically utilized for detecting or sensing a fire and can be operatively connected to the present invention so as to cause disconnection of the power lines upon occurrence of a fire.
It would, therefore, be desirable to provide a ground fault and fire detector system which will detect or sense the presence of a ground fault current or a fire for opening up a circuit breaker to disconnect the power lines from the electrical equipment to which they are connected. It would also be advantageous to provide a ground fault detector system which has the capability of readily adjusting the sensitivity or the level of the fault current that must be exceeded before the circuit breaker will open.